山羊同期发情和定时人工授精技术研究
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摘要
随着经济的发展和人民生活水平的提高,山羊生产也逐渐趋于舍饲化、规模化和程序化。如何简单易行、高效率地发挥山羊繁殖潜力、批量生产商品羊已成为急需解决的重要课题。山羊定时人工授精是通过对山羊进行同期发情处理,不用对山羊发情鉴定就能准确的进行人工授精,且保持有较高受胎率的一种程序化人工授精新方法。该技术主要包括同期发情、人工授精等技术环节。目前该技术在奶牛、肉牛和绵羊生产上得到广泛应用,但在山羊上却鲜有报道。为了探讨在不同自然条件下,比较不同山羊同期发情方法的效果,找出一种操作简单,经济实用,且能在南方农村养羊中具有普遍推广价值的方法,我们开展了山羊同期发情和定时人工授精技术研究。
     本研究分为两个部分:(1)选取相同饲养条件下乐至黑山羊健康、空怀母羊200只,分三组,分别用Ovsynch法(GnRH+PGF2α+GnRH) (n=68)、阴道栓短处理法(放置炔诺酮阴道栓7d+PGF2α) (n=68)和阴道栓长处理法(放置炔诺酮阴道栓11d+PGF2α)(n=64)进行同期发情处理,测定比较同期发情率、发情开始时间、发情持续时间;(2)乐至黑山羊公羊(n=13)精液品质检测和采用B超仪器确定人工授精的最佳时间;测定比较三种处理方法母羊的受胎率、产羔率、羔羊公母比例等,筛选一种山羊同期发情和定时人工授精方法。主要研究结果如下:
     1.在LHRH-A3三个剂量组中,用8μg剂量两次处理所获得的同期发情率为100%,且副作用相对较小,故选定8μg为Ovsynch法最佳剂量。在秋末冬初(10~11月),Ovsynch组和长期、短期处理组同期发情率分别为86.76%和85.29%、84.38%,各组间差异不显著(P>0.05)。阴道栓法长期组山羊发情开始时间比Ovsynch组与阴道栓短处理组分别多10.26h(P<0.01)和13.79h(P<0.01)。在春末夏初(5~6月),Ovsynch组和长期、短期处理组同期发情率分别为23.53%、35.29%和50.00%,阴道栓短期组显著高于Ovsynch组(P<0.05)。在发情持续时间上,阴道栓长处理组比Ovsynch组长8.25h(P<0.01),比阴道栓短处理长7.87h(P<0.01)。Ovsynch组,处女羊与经产母羊比较,同期发情率低了21.10%(P<0.05)出现发情时间提前了14.45h(P<0.01)。
     2.对13只乐至黑山羊公羊进行精液品质检测,所有精液样品均呈乳白色或灰白色、云雾状、略带腥味、无杂质。秋末冬初与春末夏初节射精量分别为0.87±0.56mL和0.93±0.27mL;精子活力分别为0.71±0.08和0.69±0.11;精子密度分别为(3.18±0.75)×109和(3.32±0.52)×109;精子畸形率分别为(8.88.±3.10)%和(8.32±2.67)%,略低于平均水平,但基本符合人工授精要求。对Ovsynch组选取10只母羊进行超声检测,检测排卵情况表明:秋末冬初(10~11月)使用Ovsynch法处理母羊同期发情以后,在12~24h共有4只母羊发生排卵;在春末夏初(5~6月)与初产母羊的检测中发现在6~12h各有1只和2只母羊发生排卵。在秋末冬初,最佳输精时间在Ovsynch法末次处理后18~24h进行;在春末夏初,不同胎次母羊的最佳输精时间还需进一步研究。在秋末冬初(10~11月)Ovsynch组和长期、短期处理组受胎率率分别为67.80%和65.52%、70.37%,各组间差异不显著(P>0.05);阴道栓短处理羔羊初生重分别比Ovsynch法和长期处理组低了210.63g(P<0.01)和145.45g(P<0.01);而产羔率上,阴道栓长处理组低于短处理组21%,低于Ovsynch组15%。在春末夏初(5~6月),Ovsynch法和长期、短期处理组受胎率率分别为62.50%和66.67%、65.63%,各组差异不显著,且均略低于秋末冬初。羔羊重长期组高于Ovsynch组218.00g(P<0.01),高于短期处理组98.26g(P<0.05);而短处理组比Ovsynch组重129.26g(P<0.05)。阴道栓长处理组产羔率比Ovsynch组高了21%,比阴道栓短处理组高了14%。在初产与经产羊上,Ovsynch组初产羊的受胎率比经产母羊低19.79%,差异极显著(P<0.01);初产羊的羔羊重、产羔率均略低于经产母羊,但差异均不显著(P>0.05)。
     结论:采用同期发情处理可以有效地促进母羊发情同期化,且排卵集中,便于开展人工授精、集中配种、同期产羔和组织山羊生产。比较同期处理方法人工授精效果,表明在秋末冬初Ovsynch法在山羊同期发情效果上优于传统孕酮阴道栓方法。
With the development of the economy and people's living standards in Southwest of China, the goat production tends to factorization and intensive management. It is the challenging and pivotal reproductive issue how simply and efficiently to reproduce the goat meat. New reproductive technology is essential to be used to solve the problem aiming to control doe ovulation with the ovulation synchronization methods and predict the accurate ovulation time. Furthermore, promoting the technicians to conduct artificial insemination at the optimum span for the high conception rate. Goat timed artificial insemination (TAI), which including estrus synchronization, artificial insemination and other technical methods, is simple, economical and practical and be one of the assisted-reproduction technologies (ART). At present, the technology in dairy cattle, beef cattle and sheep production are widely used, but there are few reports on goat. In order to explore in different natural conditions, to compare the effect of goat estrus synchronization methods, and to find a simple and effective procedure, we focus this study on estrous synchronization and fixed-time insemination in goat.
     Aiming to the difficult goat production problem, fixed artificial insemination was designed on ewes to study three sections. Firstly, choosed the healthyLezhi Black does from the same feedlot environment and conduct synchronization of estrus on them, then tested the synchronization rate, pubescence starting time and pubescence lasting time to survey the treated does' ovarian wave and judge the degree of ovulation synchronization. Secondly, a total of 13 Lezhi Black goat bucks were selected and analysed for the semen qualities. Determinate the effect of synchronization of estrus on does reproduction performance through testing kidding rate, conception rate and other parameters.
     The group of the 8μg LHRH-A3 resulted in 100% of estrus synchronization, and had relatively small side effects. Therefore the optimum concentration of LHRH-A3 using the Ovsynch method is the 8μg per doe. During the breeding season (10~11), the rates of estrus synchronization were 86.76%.85.29% and 84.38%, respectively, but the difference during the three methods was not significant (P>0.05), the pubescence starting time of Long Vagina Plug method was significantly longer than the two other methods (P<0.01); in the non-breeding season(5~6), the estrus synchronization rates of the Ovsynch, Short-plug and Long-plug were 23.53% 35.29% and 50.00%. short-plug were significantly higher than the Ovsynch group(P<0.05). The duration of the estrus, Short-plug group was 8.25h longer than the Ovsynch(P<0.01), Short-plug group was 7.87h longer than the Long-plug(P<0.01). Using Ovsynch comparing with the virgin ewe and multiparous ewe, the estrus synchronization rate of the vigin ewe had 21.10% lower than multiparous ewe(P<0.05) and occurred estrus of the vigin ewe was 14.45h earlier than multiparous ewe(P<0.01).
     Detection of semen qualities of every samples of 13 bucks showed milky white or gray, cloudy, slightly fishy smell in non-breeding season and breeding season. The volume of ejaculation was 0.87±0.56mL, and 0.93±0.27mL; The sperm motility were 0.71±0.08 and 0.69±0.11; The sperm densities were (3.18±0.75)×109 and (3.32±0.52)×109; The sperm deformations were (8.88.±3.10)% and (8.32±2.67)%, below average,but the basic character united artificial insemination requirements. Choose 10 ewes for ultrasonic testing, Ovulation testing indicate that:breeding season (10~11) treatment of ewes with Ovsynch after estrus synchronization, Ultrasonic testing Detection 4 ewes ovulation occurs in 12~24h; in the non-breeding season (5~6) and the virgin goat found in the 6~12h each 1 and 2 ovulation occurs. During the breeding season, the best time in the Ovsynch method insemination last for18~24h after treatment; in non-breeding season, the best ewes of different parity insemination time needs further study. The ovulation synchronization and fixed-time insemination did not statistically affect the reproduction performance.The experiment was conducted to study the effect of synchronization ovulation on the does'reproduction performance. Results indicate:during the reproductive season, the estrus rate of Ovsynch, Long-Plug, Short-Plug treatment were 67.80%,65.52% and 70.37%, respectively, whereas, the difference during the three methods were not obvious (P>0.05). Ovsynch treatment incrassated (P<0.01) the kid weight by 165.18g and 180.63g compared with the Long-Plug and Short-Plug treatment, Long-Plug treatment decreased (P>0.05) the kidding rate by 0.15% and 0.06%; in the non-reproductive season, the estrus rate of Ovsynch, Long-Plug, Short-Plug treatment were 62.05%,66.67% and 65.63%; Ovsynch treatment decreased the kid weight by 129.26g and 218.00g. compared with the Long-Plug and Short-Plug treatment and Ovsynch treatment (P<0.01). Long-Plug treatment increased (P>0.05) the kidding rate by 0.14% and 0.21%. The kidding rate of multiparous does was increased 19.79% than primiparous ones treated by Ovsynch method.
     In conclusion, the method of synchronization ovulation could promote the does estrus synchronization, which is convenient to intensively mating and managing production. According to the study of goat fixed-time insemination it showed the method of synchronization ovulation is preferable to the traditional methods by getting the same conception rate and kidding rate, which could afford theory evidences for the next application of intensive kidding technique.
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